Research on High Power PV Modular DC Boost System and Control Strategy

Abstract

Centralized DC boost conversion system is one of the key technologies to realize large-scale integration of PV generation. Firstly, in this paper, an active-clamp full-bridge boost converter is taken as the basic unit. Then a multi-modular converter centralized DC boosting system is proposed, which is suitable for $30\mathrm{k}\mathrm{V}/1.5\mathrm{M}\mathrm{W}$ PV grid-connected system. In this system, inputs and outputs of two active-clamp full-bridge boost converters are connected in parallel and series to form a sub-module. With input-parallel output-parallel (IPOP) scheme of multi-modules, the system can meet the demand of DC boost design with large capacity and high conversion ratio, and achieve the goal of power superposition at constant voltage. Subsequently, in order to solve the problem of input current sharing (ICS) and output voltage sharing (OVS) among sub-modules, a DC voltage sharing and current sharing control strategy is proposed. Finally, a real-time simulation model of $\pm 30\mathrm{k}\mathrm{V}/1.5\mathrm{M}\mathrm{W}$ PV modular DC boost system is built in the RT-LAB environment. Effectiveness of the structure and control strategy is validated by the simulation results.